Dispensers of samples of liquids such as miniature sprays are generally assembled after the reservoir has been filled.
The reservoir is closed by forced sealed engagement of the pump-supporting sleeve, and that can cause the pressure of the air inside the reservoir to rise excessively, particularly when no means exist for venting the compressed air.
Such excess pressure then gives rise to the liquid being suddenly squirted and sprayed when the pump is used for the first time.
A known method of avoiding such excess pressure consists in opening the vent of the pump by pressing its head down during assembly, as described in EP 408 421 (SOFAB). However, when the dispenser is delivered with a cap, it is desirable for economic reasons to assemble the pump already fitted with its cap. Under such circumstances, it is no longer possible to open its vent since the head of the pump is not accessible.
Another technique consists in making a longitudinal groove in the side wall of the sleeve or the reservoir, thereby allowing compressed air to escape, which groove is closed at its top end by a transverse shoulder, as described in U.S. Pat. No. 4,311,255 (MESHBERG).
Nevertheless, that technical solution is not satisfactory with respect to final sealing of the assembly, given that the groove is closed by walls of small area moving together and then making contact.
It is necessary not only to ensure proper venting and sealing, but also to provide mechanical cohesion between the pump and the reservoir. Unfortunately, such cohesion increases with increasing height of the radial clamping bearing surfaces on the sleeve and on the reservoir.